2. It says in the manual the input signal to the compressor should be -18dbfs otherwise it will be over compressed. I run a signal from a drum bus in to the compressor that peaks at 0dbfs and the compressor is not reacting and it doesn't sound too compressed. I am a little confused. Any extra info on this?

3. When I turn the input trim up, does the output gain attenuate even though the output gain dial does not change?

1. the product is not an endorsement, so we cannot answer here
2. there is an input trim already tuned to -18dB on the gui. It means you can use it like all other plugins frome companies, without gain staging at all at original settings
3. yes if you dial the input trim your input is hotter (and the compressor action is more). This kind of control is "compensated", so it increases the input and decreses the output accordingly and viceversa. But the compression will change (and also harmonic distortion coming from the preamp)

I have essentially the same question: the manual says that the input should be no hotter than -18dbFS, so I dropped the input down--Aquamarine is on the Master bus (in Samplitude Pro X2, in my case), just after Slate Digital's Virtual mix bus, set to show about -18dbFS on the output meter of Samplitude. I then enable Aquamarine, and all seems to be fine, but I'm still experimenting, just using the Opto compressor for now. You mention that the -18dbFS level is already set in the input trim, so this means I don't need to do what I'm doing, correct? The input trim, when set to what indicator on the dial, is -18dbFS? (I'm sorry, I don't have Aquamarine up and running right now.) Thanks! I love the sound of this plugin!